Cross-sectional studies suggest that the menopause is associated with changes in endocrine-metabolic function and body composition that may accelerate the development of osteoporosis and cardiovascular disease. The hypotheses of this longitudinal study are that the menopausal transition is associated with change before the cessation of the menses as described: 1) decreases in nocturnal secretory profile of growth hormone that, in combination with the decreases in ovarian sex hormones, contribute to changes in body composition, specifically decreases in bone mass and increases in fat mass; 2) increases in biochemical markers of bone turnover that are measured in blood and urine that predict decreases in bone mass; and 3) increases in body fat mass and fat distribution to the intra-abdominal area that are associated with adverse changes in lipid and lipoprotein profiles. The women are 110 healthy, nonsmoking participants of the Baltimore Longitudinal Study of Aging (BLSA), ages 45-55 years who are experiencing monthly menses at enrollment. They receive quarterly GCRC outpatient visits until the menses have ceased for 2 years. The visits include a menopausal symptom questionnaire, endocrine and blood lipid profiles, anthropometry, dual energy x-ray absorptiometry (DEXA), bone biochemistries, and dietary assessments.